The present invention is directed to a method of and an apparatus for coating the exterior surfaces of molded fibrous workpieces with a polymeric coating to encapsulate dust and fibers within the surfaces of the workpiece.
Molded fibrous workpieces, such as, glass fiber turning vanes used in heating, ventilating and air conditioning systems; glass, ceramic or mineral wool fiber pipe insulations; T-12 fibrous insulation; and other fibrous workpieces may have loose fibers and/or dust in their exterior surfaces. To improve the handleability of these various types of molded fibrous workpieces and, in the case of glass fiber turning vanes, to improve the acoustical performance of the workpieces when placed in heating, ventilating and air conditioning systems, the exterior surfaces can be coated. The coating, if properly applied, encapsulates any dust and loose fibers within the surface of the workpiece.
Presently, these workpieces are coated by hand spraying the coating material onto the exterior surfaces of the workpieces. This type of a coating operation is labor intensive and often results in a waste of coating material when to much coating material is applied to certain portions of the workpieces. In addition, when a coating is applied by hand spraying the coating material onto the workpiece, it is difficult to obtain a smooth, evenly distributed coating on the surface of the workpiece or to even determine whether or not the coating operation has provided a coating that completely covers the entire exterior surface of the workpiece. Thus, there has been a need to provide a simple, yet effective and efficient, method of and apparatus for coating such molded fibrous workpieces that applies a smooth, evenly distributed coating over the entire exterior surface of these workpieces and encapsulates dust and loose fibers within the exterior surfaces of the workpieces.